﻿Yol. 66, ,] THE WESTERN END OF THE WEALD. 6-11 



Topley (5, p. 473, footnote) ' to have been first used by Ramsay in 

 1847 ; but the words themselves are not to be found in the abstract 

 of his paper to which they refer (20). It was not until 1863 that 

 he definitely pointed to the Wealden area as showing traces of such a 

 plain (21, 1st ed.); and in this he was anticipated by Jukes (8, p. 400), 

 who, in 1862, expressed the belief that marine denudation had 

 removed the Chalk from the centre of that area i during or after the 

 Eocene Period/ leaving subaerial agencies to complete the process. 

 Some years later Topley (26) adopted the same hypothesis, and, by 

 adding to Ramsay's very meagre evidence a table of heights along 

 longitudinal and transverse lines, placed it on a more satisfactory 

 footing : but even by Topley the arguments in its favour are not 

 clearly defined, and I cannot help suspecting that its wide acceptance 

 at that time may have been due, not so much to the strength of the 

 proofs advanced, as to an unwillingness on the part of those who 

 were compelled to give up the sea-cliff: theory to abandon altogether 

 their belief in marine action. 



Dr. Barrois, in his classical paper on the English Chalk (1), found 

 no evidence of this marine plain, which he thought was postulated by 

 Ramsay solely to explain the courses of the consequent rivers. In 

 his opinion the subaerial denudation of the Weald began before the 

 Eocene beds were laid down, and continued at least until Pliocene 

 times : how far the Diestian sea may have invaded the district is 

 left uncertain, but it is expressly stated that it produced very little 

 effect in denuding the Chalk. 



Prestwich also rejected the hypothesis that the sea had played 

 any important part in the removal of the Chalk from the Wealden 

 area. According to him (17, 18, & 19) that area has formed dry land 

 since Eocene, and perhaps since pre-Eocene, times ; and although 

 the early Pliocene sea has left deposits along its northern borders 

 as far west as Dorking, yet it did not extend for any distance into 

 the interior. 



Prof. W. M. Davis (3), in 1895, put forward a suggestion which, 

 so far as this region is concerned, seems to have been entirely new. 

 From his study of the courses of rivers in the south and east of 

 England he was led to the conclusion that they represented the 

 product of two cycles of subaerial denudation. The first cycle 

 ended in a peneplain, on which a mature system of drainage was 

 already established ; then a further elevation of the land initiated a 

 second cycle, the rivers of which, instead of being developed de novo 

 (as they must be on a marine plain), started with, and continued 

 still further to mature, the system already established on the 

 peneplain. 



Though many others have expressed a passing opinion on the 

 subject, practically the whole of the evidence until now adduced 

 is to be found in the writings of the five great authorities already 

 quoted — Ramsey, Topley, Barrois, Prestwich, and Davis. That 

 evidence I shall now proceed to examine in detail. 



1 These numerals in parentheses throughout the paper refer to the Biblio- 

 graphy, § IV, pp. 691-92. 



